Conventional telecommunications networks include two distinct communication pathways or subnetworks—a voice network and a signaling network. These two networks function in a cooperative manner to facilitate calls between users. As implied by its name, the voice network handles the transmission of voice (or user data) information between users. The signaling network has a number of responsibilities, which include call setup, call tear down, and database access features. In simple terms, the signaling network facilitates the dynamic linking together of a number of discrete voice-type communication circuits such that a voice-type connection is established between the calling and called party. Additionally, the signaling network provides a framework through which non-voice-related information may be transported, with this data and transport functionality being transparent to the users. The signaling protocol most commonly employed in communication networks around the world is the signaling system 7 (SS7) protocol.
From a hardware perspective, an SS7 network includes a number of SS7 nodes, generically referred to as signaling points (SPs), that are interconnected using signaling links, also referred to as SS7 links. At least three major types of SPs are provided in an SS7 network: service switching points (SSPs), signal transfer points (STPs), and service control points (SCPs). Within an SS7 signaling network, each SP is assigned an SS7 network address, which is referred to as a point code (PC).
An SSP is normally installed in Class 4 tandem or Class 5 end offices. The SSP is capable of supporting SS7 signaling operations. An SSP can be a customer switch, an end-office, an access tandem, and/or a tandem. An STP transfers signaling messages from one signaling link to another. STPs are packet switches and are generally installed as mated pairs for reliability and redundancy. Finally, SCPs host one or more databases, such as 800 number translation databases, 800 number carrier identification databases, credit card verification databases, home location registers, visitor location registers, mobile location servers, etc.
A simplified example of an SS7 signaling network is presented in FIG. 1. In FIG. 1, SS7 signaling network 10 includes a mated pair of STPs 12. Mated STP pair 12 includes an STP node 14 and an STP node 16, where STP node 14 is assigned an SS7 point code of 1-0-1 and STP node 16 is assigned a point code of 1-0-2. Network 10 also includes an SSP or end office (EO) 18. In conventional SS7 networks, each SS7 network element is assigned a point code that uniquely identifies each node within the context of the SS7 network. The point code that a node advertises to other nodes in the network for routing purposes is sometimes referred to as a true point code. In addition to the true point code, mated signal transfer points may be assigned an additional point code used to uniquely identify the pair. This shared point code is sometimes referred to as a capability point code (CPC). Accordingly, other network elements may send signaling messages to one mate of an STP pair using either the true point code associated with the individual node or the shared capability point code assigned to the mated pair. In either case, it should be noted that both the true point code and the CPC are public network addresses made available to other network elements in the PSTN for routing purposes. Thus, in FIG. 1, STPs 14 and 16 and end office 18 advertise separate public point codes to the PSTN.
As the convergence of traditional SS7 telecommunication signaling networks and traditional IP-centric data networks evolves, so will the tendency of network operators to place SSP end office node functionality within the data network or IP component of a converged network environment. That is to say, PSTN and wireless telephone network operators will likely find the economics of data network operation favorable to the placement of end office nodes within the data component of the converged network environment, as opposed to the traditional PSTN-SS7 network component. Such data network SSP-like network elements include media gateway (MG) and media gateway controller (MGC) or “softswitch” (SS) nodes, both of which are well known to those skilled in the art of Internet protocol (IP) telephony.
In a converged SS7-IP network environment, such SSP-like network nodes that would traditionally have resided within an SS7 signaling network and been assigned a unique SS7 network address (i.e., a point code) may now be located within an IP network and assigned a corresponding IP network address. However, in addition to IP addresses, such IP-based SSPs or end offices have also required SS7 point codes in order to be accessible to and inter-operable with other nodes in the SS7 network component. Consequently, network operators that choose to deploy IP-based signaling nodes (e.g., MGC/softswitch nodes) that also communicate with SS7 nodes have been faced with point code shortages because of the requirement that each SS7/IP node have its own point code in addition to an IP address.
One possible solution to the point code shortage problem between SS7 and IP networks is point code sharing, as described in commonly assigned, co-pending U.S. patent application Ser. No. 10/222,457, entitled Methods and Systems for Providing End Office Support in a Signaling Network (hereinafter, “the Parent Application”). The Parent Application discloses a routing node capable of sharing a point code with a remote application. The routing node utilizes an internal point code to distribute messages within the routing node. The remote application is not required to have its own separate point code. Rather, the remote application shares the point code of the routing node to which it is connected. Thus, the invention described in the Parent Application mitigates the point code usage problems. The Parent Application also describes a method for preventing failure of one remote application from disabling communications with another remote application.
Some commercially available signaling routers, such as SAVVI line of signaling products presented at www.radysys.com, are described as having the capability to communicate between SS7 and IP nodes. However, these products are not known to have a distributed architecture where SS7 routing data is distributed among multiple processors or cards. If routing between SS7 and IP nodes is handled by a single processor, the problem of routing messages between these nodes and performing network management on behalf of these nodes is greatly simplified because all messages are processed by the same processor. However, using a single processor to route and process all messages is undesirable for reliability and performance reasons. Accordingly, there exist a long felt need for methods and systems for routing messages within and between a mated pair of routing nodes with a distributed processing architecture and one or more redundantly connected remote applications.